1. Field of the Invention
The present invention relates to a heterogeneous polymer gel comprising at least two gel networks. The heterogeneous polymer gel exhibits controlled changes in volume in response to external environmental changes.
2. Description of the Related Art
Relatively uniform or homogeneous polymer gels have attracted much interest because their volume can be changed by several orders of magnitude in response to the change of an external factor such as solvent, temperature, electric field, or light. Uses of such homogeneous polymer gels include such applications as artificial muscles, drug-delivery devices, chemical valves and actuators, and magnetic resonance monitoring agents.
It is desirable to develop and produce new polymer gels that exhibit desired reversible characteristics in response to external environmental changes.